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Heritage Science

Table 2 Iron and Manganese percentage of stained granite samples and CIELAB color coordinates

From: Green chitosan: thiourea dioxide cleaning gel for manganese stains on granite and glass substrates

Granite sample

Elemental analysis

CIELAB coordinates

Fe (%)

Mn (%)

Mn/Fe

L*

a*

b*

I

1.68 ± 0.09

2.97 ± 0.24

1.77

27.29 ± 0.40

3.42 ± 0.18

9.74 ± 0.32

II

2.23 ± 0.02

2.76 ± 0.09

1.24

38.69 ± 0.03

3.50 ± 0.01

6.74 ± 0.01

III

0.86 ± 0.04

1.87 ± 0.31

0.65

38.27 ± 0.30

3.28 ± 0.19

9.55 ± 0.40

  1. L* lightness, a* red/green value, b* yellow/blue value
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